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Drought Dries Up California Hydropower

As California’s historic drought dries up the state’s water supplies and withers its crops, it’s also shaking up the way electricity is produced there.

There’s so little water available in the state’s reservoirs that California’s ability to produce hydropower has been cut in half, while its use of renewables and natural gas power has spiked, a U.S. Energy Information Administration report published Monday shows.

Current hydropower generation in California compared to the 10-year average.
Credit: EIA

Normally, 20 percent of California’s power comes from hydroelectric sources. But not anymore.

For the first six months of 2014, only 10 percent of the state’s electricity was hydropower, roughly between 900,000 megawatt hours in January and 2.3 million megawatt hours in June, EIA data show. The average hydropower generation for January is about 2 million megawatt hours, and nearly 4 million megawatt hours in June.

Most of California has been mired in an extreme or exceptional drought since 2011, a phenomenon that recent studies show has a complicated connection to climate change. As of the latest drought monitor, more than 58 percent of California is experiencing the most intense drought conditions, while the entire state is currently seeing some level of severe or extreme drought.

Nearly all of California’s reservoir levels are below average for this time of year, with the water level of Lake Shasta, one of the state’s largest reservoirs, currently sitting at 42 percent of historical average, said California Department of Water Resources spokesman Ted Thomas.

Conditions are so dire that the California State Water Project, which provides supplemental water to 29 public water agencies, can only deliver 5 percent of the amount of water those agencies requested this year, he said.

With less water filling the state’s reservoirs than usual, hydroelectric dams’ ability to produce electricity is drastically reduced.

The latest drought monitor from NOAA and the University of Nebraska-Lincoln.
Credit: U.S. Drought Monitor

Early this year, the California Energy Commission estimated that the state’s major utilities together would face a 63 percent shortfall in hydropower generation this year, according to a commission Hydropower Working Group briefing on the matter.

As hydropower production drops, natural gas power generation is taking up the slack, hitting a 10-year high in California in January, just as hydropower generation hit a 10-year low. Natural gas power generation for the first half of this year was 16 percent above the January-June average for the previous decade, EIA data show.

Wind power generation surpassed hydropower generation for the first time in California in February and March, contributing to a more than 17 percent spike in solar and wind power generation in California and making up roughly 30 percent of the state’s total power supply.

The upshot of this is that the nation’s most populous state is using more low-carbon wind and solar than power than ever before, but the state’s other major source of low-carbon energy — hydropower — is declining as the drought shows no sign of abating any time soon.